The present invention relates to a combustion chamber. In a preferred embodiment, this invention relates to a combustion chamber to be employed in a radiant heating system. In an especially preferred embodiment, this invention is concerned with a combustion chamber to be employed in a high heating capacity, positive-pressure, single-pass radiant heating system employing an oil-fired burner as the heat source.
Infra-red radiant heating systems have become of considerable importance, especially for heating large spaces such as factories, aircraft hangars and the like. Such systems have become of even more importance with the worsening fuel crisis and the increasing concern over atmospheric pollution because they are more efficient and "cleaner" than other heating systems. Thus the use of radiant heating systems in place of more conventional heating systems will reduce fuel consumption and atmospheric pollution.
As originally conceived, such systems employed a porous, ceramic mat as the heating element. Fuel gas was passed through the pores of the mat and burned at the outer surface, causing the mat to heat up and emit infra-red radiation. Because of the danger inherent in open-flame devices of this type, systems in which a fuel is burned in a combustion chamber and the products of combustion are conducted through an elongated conduit to cause the conduit to be heated and emit infra-red radiation were developed. Systems of this type are disclosed, for example, in U.S. Pat. Nos. 2,946,510 to Galvin, 3,399,833 to Johnson and 3,416,512 to Mintz. In these systems the conduit is not heated to the point of emitting visible light. Although the use of oil-fired burners has been suggested, in actual practice gas-fired burners have been employed as the heat source. Because the current fuel crisis is most critical with respect to gas, oil-fired systems are particularly desired today.
In one form of these systems, a closed loop circuit is employed in which the combustion products are recirculated through the heating conduit to eliminate the need to heat air from ambient temperatures up to combustion temperatures, and thus improve the heat efficiency of the system. However, systems of this type are complex and expensive to install, and since the heat capacity of air is small, there is little practical value to such systems.
Other systems employ a single-pass concept in which the combustion gases are not recycled, but are exhausted from the heating conduit to the atmosphere, either directly or through a stack. In general, such systems require some means to induce the flow of combustion gas through the heating conduit. In the single-pass system this means has comprised an exhaust fan mounted at the exit end of the heating conduit which draws the combustion gases through the conduit. As a result, the system is a vacuum system, a feature which is claimed to be advantageous because, in the event a leak develops, combustion gases will not be vented to the area being heated. Unfortunately, this advantage has proven to be illusory in practice, and such systems can be extremely dangerous in the event of a failure of the exhaust fan. In this case, air is not removed from the vicinity of the burner and the burner overheats, frequently to the point of causing the adjacent tubing to emit a visible glow, thus presenting an obvious fire hazard, as well as the possibility of damage to the heating system. Safety devices have been developed to avoid this danger, but they increase the cost and complexity of the system and are themselves prone to failure.
Finally, the currently available systems have relatively low heat capacities, generally not greater than 100,000 Btu/hour, although in some cases units having capacities of up to 140,000 Btu/hour are available. Accordingly, it has been found necessary to employ several independent heating systems in parallel, or systems in which a series of burners are spaced along a single conduit where greater heating capacity was desired.
It is an object of this invention to provide an improved radiant heating system.
It is a further object of this invention to provide a positive-pressure radiant heating system.
A further object of this invention is to provide an oil-fired radiant heating system.
A still further object of this invention is to provide a high heating capacity radiant heating system.
Another object of this invention is the provision of a positive-pressure, high heating capacity, single-pass, oil-fired radiant heating system.
Still another object of this invention is the provision of a combustion chamber especially adapted for use in an oil-fired radiant heating system as descirbed above.